Trusting startups to dispose of it properly if they go bankrupt seems like an absolute disaster waiting to happen. Netflix has/had an interesting series "radioactive emergency" based on real events that seems to be a fairly plausible outcome. The "Goiânia accident in Brazil occurred on September 13, 1987".
Yeah, apparently the original library has nearly 4,000 tests. This would have been impossible without those. This speaks to the power of testing. The lack of discussion here also shows how under-valued it is.
I stopped reading at "The competition itself was a beginner-friendly offensive security CTF..."
Beating a bunch of inexperienced people does not impress me, and is poor sportsmanship as well.